(1) Field of the Invention
This invention relates to a device for measuring parameters during flight tests of an aircraft, and a method making use of this device.
(2) Description of Related Art
Sensors, particularly pressure and noise sensors, must be placed on the outside surface of aircraft during tests to measure corresponding parameters during the flight. They may also be placed in holes formed in the aircraft, but obviously this method of working causes damage and will not be preferred; it is impossible if tanks or other equipment are located just behind the surface.
Sensors are then surface mounted on the aircraft through a support. In one known design, the support is a rigid aluminum disk, and the sensor is located on the top surface of this disk. The disk and the outside surface of the aircraft are bonded together using double-sided adhesives.
This design has several disadvantages. Firstly, it may be difficult to make the disk bond to the aircraft surface because the curvature of the aircraft is usually different from the curvature of the disk. This curvature also makes it necessary to close off the gap occurring between the periphery of the disk and the outside surface of the aircraft by a mastic seal, which is difficult to install so that it becomes necessary to wait for polymerization for several hours while protecting the seal and possibly correcting any defects. It is also difficult to disassemble the disk after the test, because the mastic has to be removed and then the bonding adhesive has to be cut, which is located not far from the center of the disk, by inserting a blade under the disk and then working blind, with the risk of damaging the aircraft surface. Finally, the tests themselves are often distorted by the fairly thick disk that forms relief on the surface of the aircraft, even if the periphery of the disk is beveled to prevent an excessively sudden surface discontinuity.
Another support design provides a means of reducing this latter disadvantage of distorting the measurements. One embodiment is described in French patent 2 749 656: the support then comprises a thin plate with a large surface area that is custom made to follow the curvature of the aircraft surface at the location at which it must be installed. The plate and the aircraft surface can also be bonded together using a double-sided adhesive, but this adhesive is sufficiently thick so that there is a gap between the plate and the aircraft surface, inside which the sensors are housed.
It is obvious that custom manufacturing of the plate is expensive and slow. The disadvantages are the same as for the mastic seal, since the mastic seal still needs to be used to fill in the gap between the periphery of the plate and the aircraft structure. Finally, the plate is always destroyed during disassembly and therefore can only be used once. It should also be added that this design is not suitable for noise sensors that have to be connected to the plate and therefore installed with it, with the risk of damaging them that is unacceptable due to their cost.
A new sensor support is proposed in this technical field as an improvement for the previous supports. The design of a small approximately disk-shaped support is reused, but differently. The new design enables easy assembly and disassembly of a support that is easily made and that has very little effect on the measurements, particularly even more than when a thin plate is used.